Why would you need to change the script? If you make changes to the macro, it's not going to make any difference to HKN. You'll have 2 macros and all HKN will do is alternate between the two. You put your main macro on 2 and the pet macro on shift 2 for example -
yes this seems all well and good but im thinking that its casting mend pet every other click which means that its hella slowing the dps macro down

its doing in the case of what you've put here

serpent sting,mend pet,kill command,mend pet,arcane shot,mend pet,steady shot,mend pet,steady shot,mend pet,steady shot
If this is wrong please tell me how
also i haven't paid close attention but is mend pet on the GCD